1. Field of the Invention
The present invention relates to a cover structure of a machine tool.
2. Description of the Related Art
In order to secure the safety of an operator and to prevent chips and coolant from scattering around a machine tool, the machining space of the machine tool is covered with a cover in many cases. Also, a slide door is provided in a part of the cover to facilitate placement and retrieval of a workpiece, and other operations. Further, in many cases, electronic devices, such as a CNC (numerical controller for controlling the machine tool) and an operation panel, are provided on the cover, especially on a fixed cover located on the closing direction side of the slide door.
In some use cases, the slide door of the machine tool may be opened and closed as frequently as 1000 times or more per day, and may also be opened and closed much quickly in order to increase the production efficiency. For this reason, it is necessary to devise something to reduce a shock due to the opening and closing of the slide door so as to prevent the devices provided on the cover, such as the CNC and the operation panel, from being damaged by the shock.
To cope with this, for example, Japanese Utility Model Laid-Open No. 5-340 discloses a cover structure of a machine tool, which is provided with an opening portion of a splash guard surrounding the machining space of the machine tool, the opening portion being used for carrying in and out a workpiece, a fixed cover formed around the opening portion, first and second slide doors movably provided to open and close the opening portion and provided so as to cover the opening portion, and sliding contact members respectively attached to the first and second slide doors. The sliding contact member is always brought into sliding contact with the first slide door or the second slide door. When the first slide door is moved, the sliding contact member makes the second slide door follow the first slide door. When the second slide door reaches a movement end, the sliding contact member allows only the first slide door to be moved.
Further, a method has conventionally been adopted, in which a cushioning material, such as cushion rubber, is attached to the closing-direction end surface of the slide door, so as to reduce a shock generated at the time when the slide door collides with the fixed cover provided on the closing-direction side of the slide door. FIG. 22 is a view explaining a conventional cover structure where a slide door is provided inside the machine tool and opened. FIG. 23 is a view explaining a state where the slide door is closed in the cover structure of FIG. 22. FIG. 24 is a view explaining a cross section of the cover structure of FIG. 23.
As shown in FIG. 22, an opening portion is provided in a fixed cover 2 surrounding the inside portion of the machine-tool, which is the machining space of the machine tool, and a slide door 4 used for an operation, such as taking a workpiece into and out of the machining space, is provided in the opening portion. Electronic devices 8, such as a numerical controller (CNC) and an operation panel, are attached to the side surface of the fixed cover 2. Further, a shock absorbing member 6, such as cushion rubber or cushion sponge, is attached to the closing-direction-side end surface of the slide door 4, in order to absorb a shock due to a collision between the closing-direction-side end surface of the slide door 4 and the slide-door-closing-side end surface of the opening portion of the fixed cover 2 caused at the time when the slide door 4 is closed as shown in FIG. 23 and FIG. 24. As shown in FIG. 24, when the slide door 4 is closed, the shock caused by the collision between the slide door 4 and the side end surface of the fixed cover 2 is reduced by the shock absorbing member 6 in the portion indicated by reference numeral 110. In this case, in the portion indicated by reference numeral 110, the side end surface of the slide door 4, where the shock absorbing member 6 is attached, is first brought into contact with the side end surface of the fixed cover 2, and then, in the portion indicated by reference numeral 100, the side end surface of the slide door 4 is brought into contact with the side end surface of the fixed cover 2 or is not brought into contact with the side end surface of the fixed cover 2.
Note that FIG. 25 to FIG. 27 show an example of a cover structure of a machine tool in which a slide door 14 is provided outside the machine tool. FIG. 25 shows a state where the slide door is opened, and FIG. 26 shows a state where the slide door is closed. Further, FIG. 27 is a view explaining a cross section of the cover structure of FIG. 26. The cover structure shown in FIG. 25 to FIG. 27 is similar to the structure described above with reference to FIG. 22 to FIG. 24, and hence the description thereof is omitted.
In some use cases, the slide door of the machine tool may be opened and closed as frequently as 1000 times or more per day and may also be opened and closed much quickly in order to increase production efficiency. Therefore, in the cover structure described in Japanese Utility Model Laid-Open No. 5-340, the wear of the sliding contact member is large, and the slide door cannot be opened and closed quickly.
Further, in the cover structure of the machine tool, which is described with reference to FIG. 22 to FIG. 27, each of shock absorbing members 6 and 16, such as cushion rubber and cushion sponge, is attached to the closing-direction-side end surface of each of the slide doors 4 and 14, in order to absorb a shock due to a collision between the closing-direction-side end surface of each of the slide doors 4 and 14, and the slide-door-closing-side end surface of the opening portion of each of the fixed covers 2 and 12. In this cover structure of the machine tool, wearing and falling off of each of the shock absorbing members 6 and 16, such as cushion rubber and cushion sponge, are caused due to the shock at the time of closing the slide door, and due to the influence of chips, coolant, and the like. As a result, when the slide door is closed, the shock due to the collision between the slide door and the fixed cover is increased, and thereby electronic devices, such as a numerical controller and an operation panel, provided on the fixed cover, may be damaged.